Thermoplastic elastomer composition and molded body thereof

ABSTRACT

A thermoplastic elastomer composition contains components (A) to (D), wherein the content of the component (A), (B), (C) and (D) is, respectively, 26% by weight or more and 59% by weight or less, 2% by weight or more and 9% by weight or less, 16% by weight or more and 61% by weight or less and 11% by weight or more and 56% by weight or less, when the total amount of the components (A) to (D) is 100% by weight, and the ratio of the content of the component (C) to the content of the component (D) is over 1 and 5 or less.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional of U.S. patent application Ser. No.15/963,068, filed Apr. 25, 2018, which claims priority under 35 U.S.C. §119(b) to Japanese Patent Application No. 2017-089357, filed on Apr. 28,2017, the disclosures of which are incorporated herein by reference intheir entireties.

FIELD OF THE INVENTION

The present invention relates to a thermoplastic elastomer compositionand a molded body thereof.

BACKGROUND OF THE INVENTION

Olefin-based thermoplastic elastomer compositions have been widely usedin automobile interior parts, automobile exterior parts, electric parts,home electronics parts, furniture parts, footwear parts, andarchitectural parts.

In order to adapt to the required performance of each part, a compositemolded body in which a molded body comprising a thermoplastic elastomercomposition and a molded body comprising a material other than athermoplastic elastomer composition are welded with each other is usedin some cases as the part. Patent Document 1 describes a compositemolded body in which a molded body comprising a thermoplastic elastomercomposition containing a propylene-based polymer and anethylene-propylene-based copolymer rubber and a molded body comprising apropylene-based polymer are welded with each other.

PRIOR ART DOCUMENT Patent Document

[Patent Document 1] JP-A No. 2009-40042

SUMMARY OF THE INVENTION

Recently, parts which are usable in an extensive environment from lowtemperatures to high temperatures are required, and it is required for amolded body comprising a propylene-based polymer of a molded bodycomprising a thermoplastic elastomer composition to improve rigidity athigh temperature, impact strength at low temperature and weldingstrength.

Under such circumstances, the problem to be solved by the presentinvention is to provide a thermoplastic elastomer composition capable ofgiving a molded body excellent in rigidity at high temperature, impactstrength at low temperature, and welding strength to a molded bodycomprising a propylene-based polymer.

The present invention includes inventions described in the following [1]to [14].

[1] A thermoplastic elastomer composition comprising

a component (A), a component (B), a component (C) and a component (D),wherein

the content of the component (A) is 26% by weight or more and 59% byweight or less,

the content of the component (B) is 2% by weight or more and 9% byweight or less,

the content of the component (C) is 16% by weight or more and 61% byweight or less and

the content of the component (D) is 11% by weight or more and 56% byweight or less

when the total amount of the component (A), the component (B), thecomponent (C) and the component (D) is 100% by weight, and

the ratio of the content of the component (C) to the content of thecomponent (D) is over 1 and 5 or less.

Component (A): a polymer comprising a monomer unit derived frompropylene, wherein the number of a monomer unit derived from propyleneis over 85% and 100% or less when the total number of all monomer unitscontained in the polymer is 100%, and the intrinsic viscosity ([CA]) is1.05 dl/g or more.

Component (B): a copolymer comprising a monomer unit derived fromethylene and a monomer unit derived from at least one selected from thegroup consisting of propylene and α-olefins having a number of carbonatoms of 4 or more and 12 or less, wherein the number of a monomer unitderived from ethylene is 15% or more and less than 60% when the totalnumber of all monomer units contained in the copolymer is 100%, and theintrinsic viscosity ([RB]) is 5.5 dl/g or more.

Component (C): a copolymer comprising a monomer unit derived fromethylene and a monomer unit derived from at least one selected from thegroup consisting of α-olefins having a number of carbon atoms of 5 ormore and 12 or less, wherein the number of a monomer unit derived fromethylene is 83% or more and less than 93% when the total number of allmonomer units contained in the copolymer is 100%.

The component (D): a copolymer comprising a monomer unit derived fromethylene and a monomer unit derived from at least one substance selectedfrom the group consisting of propylene and α-olefins having a number ofcarbon atoms of 4 or more and 12 or less, wherein the number of amonomer unit derived from ethylene is 60% or more and less than 83% whenthe total number of all monomer units contained in the copolymer is100%.

[2] The thermoplastic elastomer composition according to [1], whereinthe melt flow rate of the component (C) measured at a temperature of190° C. and a load of 21.18 N is 0.01 g/10 min or more and 2 g/10 min orless

[3] The thermoplastic elastomer composition according to [1] or [2],wherein the component (D) is a copolymer comprising a monomer unitderived from ethylene and a monomer unit derived from at least oneselected from the group consisting of propylene and α-olefins having anumber of carbon atoms of 4.

[4] The thermoplastic elastomer composition according to any one of [1]to [3], wherein the density of the component (D) is 0.850 g/cm or moreand less than 0.865 g/cm³.

[5] The thermoplastic elastomer composition according to any one of [1]to [4], wherein the melt flow rate of the component (D) measured at atemperature of 190° C. and a load of 21.18 N is 0.01 g/10 min or moreand 0.7 g/10 min or less.

[6] The thermoplastic elastomer composition according to any one of [1]to [5], wherein the component (C) is a copolymer comprising a monomerunit derived from ethylene and a monomer unit derived from an α-olefinhaving a number of carbon atoms of 8.

[7] The thermoplastic elastomer composition according to any one of [3]to [6], wherein the component (D) is a copolymer comprising a monomerunit derived from ethylene and a monomer unit derived from an α-olefinhaving a number of carbon atoms of 4.

[8] The thermoplastic elastomer composition according to any one of [1]to [7], wherein the component (A) is a mixture comprising a polymer(A-1) having an intrinsic viscosity of over 0.7 dl/g and 1.1 dl/g orless and a polymer (A-2) having an intrinsic viscosity of over 1.1 dl/gand 10 dl/g or less.

[9] A process for producing the thermoplastic elastomer compositionaccording to any one of [1] to [8], comprising a step of melt-kneadingthe component (A), the component (B), the component (C) and thecomponent (D).

[10] A molded body comprising the thermoplastic elastomer compositionaccording to any one of [1] to [8].

[11] A composite molded body in which a first molded body comprising apropylene-based polymer and a second molded body comprising athermoplastic elastomer composition are welded with each other, whereinwhen the cross-sectional surface perpendicular to the welding surface isstained with a vapor of ruthenium tetraoxide, the stained domainsatisfies the requirement (1);

Requirement (1): when the stained cross-sectional surface is observedwith a transmission electron microscope, D7 is 115 nm or less,

wherein D7 is the number-average circle-equivalent diameter of thestained domain in a square having a side of 4 μm around a point wherethe distance from the welded part is 7 μm in a vertical direction,wherein the square presents in the second molded body.

[12] The composite molded body according to [11], wherein when thecross-sectional surface perpendicular to the welding surface is stainedwith a vapor of ruthenium tetraoxide, the stained domain satisfies thefollowing requirement (2);

Requirement (2): when the stained cross-sectional surface is observedwith a transmission electron microscope, D200/D7 is 3.5 or more,

wherein D200 is the number-average circle-equivalent diameter of thestained domain in a square having a side of 4 μm around a point wherethe distance from the welded part is 200 μm in a vertical direction,wherein the square present in the second molded body.

[13] The composite molded body according to [11] or [12], wherein thefirst molded body and the second molded body are vibrated and weldedwith each other.

[14] An automobile interior part comprising the composite molded bodyaccording to any one of [11] to [13].

Effect of the Invention

According to the present invention, a molded body excellent in rigidityat high temperature, impact strength at low temperature and weldingstrength to a molded body comprising a propylene-based polymer can beobtained.

BRIEF EXPLANATION OF DRAWING

FIG. 1 is a schematic view of a composite molded body.

FIG. 2 is a schematic view of a composite molded body which is used formeasurement of welding strength.

DETAILED DESCRIPTION OF THE INVENTION Definition

In the present specification, “propylene-based polymer” denotes apolymer having a monomer unit derived from propylene in which the numberof the monomer unit derived from propylene is over 85% when the totalnumber of all monomer units contained in the polymer is 100%.

In the present specification, “ethylene-based copolymer” denotes apolymer having a monomer unit derived from ethylene and a monomer unitderived from at least one monomer other than ethylene in which thecontent of the monomer unit derived from ethylene is 15% or more and 99%or less when the total amount of all monomer units contained in thepolymer is 100%.

In the present specification, “α-olefin” denotes an olefin in which acarbon-carbon double bond is located at the α position.

In the present specification, “welding” means that a prescribed surfaceof a certain molded body and a prescribed surface of another molded bodyare melted to bond with each other.

In the present specification, “melting temperature” denotes the peaktemperature which is the peak temperature of the highest endotherm peakamong endothermic peaks in the melting curve measured by the followingdifferential scanning calorimetry.

<Condition of Differential Scanning Calorimetry>

Using a differential scanning calorimeter, an aluminum pan having about5 mg of an enclosed sample is (1) kept at 220° C. for 5 minutes, then,(2) cooled from 220° C. to −90° C. at a rate of 5° C./min, then, (3)heated from −90° C. to 200° C. at a rate of 5° C./min, under a nitrogenatmosphere. The differential scanning calorimetry curve obtained bycalorimetry in step (3) is the melting curve.

In the present specification, the term “melt kneading” denotes kneadingat least at a temperature at which a thermoplastic resin melts or at ahigher temperature.

<Component (A)>

The component (A) is a polymer having a monomer unit derived frompropylene in which the number of a monomer unit derived from propyleneis over 85% and 100% or less when the total number of all monomer unitscontained in the polymer is 100%,

and the intrinsic viscosity ([nA]) is 1.05 dl/g or more.

The component (A) may have a monomer unit derived from a monomer otherthan propylene. The monomer unit other than propylene includes ethyleneand α-olefins having a number of carbon atoms of 4 to 12.

The component (A) includes a propylene homopolymer and a propylenerandom copolymer.

The propylene random copolymer includes

(1) a propylene-ethylene random copolymer in which the number of amonomer unit derived from propylene is over 85% and 99.2% or less andthe number of a monomer unit derived from ethylene is 0.8% or more andless than 15%, when the total number of a monomer unit derived frompropylene and a monomer unit derived from ethylene is 100%;

(2) a propylene-ethylene-α-olefin random copolymer in which the numberof a monomer unit derived from propylene is over 85% and 98.5% or less,the number of a monomer unit derived from ethylene is 0.15% or more andless than 15% and the number of a monomer unit derived from an α-olefinhaving a number of carbon atoms of 4 or more and 12 or less is 0.03% ormore and less than 15%, where the total number of a monomer unit derivedfrom propylene, a monomer unit derived from ethylene and a monomer unitderived from an α-olefin having a number of carbon atoms of 4 or moreand 12 or less is 100%; or

(3) a propylene-α-olefin random copolymer in which the number of amonomer unit derived from propylene is 92.5% or more and 99.8% or lessand the number of a monomer unit derived from an α-olefin having anumber of carbon atoms of 4 or more and 12 or less is 0.2% or more and7.5% or less, when the total number of a monomer unit derived frompropylene and a monomer unit derived from an α-olefin having a number ofcarbon atoms of 4 or more and 12 or less is 100%. The number of amonomer unit derived from ethylene and the number of a monomer unitderived from at least one selected from the group consisting ofpropylene and α-olefins having a number of carbon atoms of 4 or more canbe determined by infrared spectroscopy.

The α-olefin having a number of carbon atoms of 4 or more and 12 or lessincludes 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene,1-decene, 1-undecene, 1-dodecene, 3-methyl-1-butene, 3-methyl-1-pentene,4-methyl-1-pentene, 2-ethyl-1-hexene, and 2,2,4-trimethyl-1-pentene. Theα-olefin having a number of carbon atoms of 4 or more and 12 or less ismore preferably an α-olefin having a number of carbon atoms of 4 or moreand 10 or less, further preferably 1-butene, 1-hexene or 1-octene. Theα-olefin having a number of carbon atoms of 4 or more may be used singlyor two or more kinds of the α-olefins may be used in combination.

The component (A) can be obtained by polymerizing propylene in thepresence of a catalyst for olefin polymerization. The catalyst forolefin polymerization includes complex type catalysts such as aZiegler-Natta type catalyst, a metallocene type complex, and anon-metallocene type complex. The polymerization method includes aslurry polymerization method, a solution polymerization method, a bulkpolymerization method, and a gas-phase polymerization method.

The intrinsic viscosity ([nA]) of the component (A) is preferably 1.05dl/g or more and 2.0 dl/g or less, more preferably 1.07 dl/g or more and1.8 dl/g or less, further preferably 1.1 dl/g or more and 1.6 dl/g orless, from the standpoint of impact strength at low temperature of amolded body.

In the present specification, the reduced viscosity is measured intetralin at 135° C. using a Ubbelohde type viscometer, and the intrinsicviscosity is determined by an extrapolation method according to acalculation method described in “Polymer Solution, Polymer Experiment(Kobunshi Jikkengaku) 11” (published by Kyoritsu Shuppan Co., Ltd.,1982) p. 491.

The thermoplastic elastomer composition according to the presentinvention may contain only one kind of the component (A), or may containtwo or more kinds of the component (A).

When the thermoplastic elastomer composition contains two or more kindsof the component (A), if [ηA] determined by substituting the intrinsicviscosity of each component (A) into the formula (1) is 1.05 dl/g ormore, a mixture of the two or more kinds of the component (A) is“component (A)”.[ηA]=Σ([η_(Ai)]×m _(Ai))/Σ[m _(Ai)]  (1)

Component (A-i): a polymer comprising a monomer unit derived frompropylene in which the number of the monomer unit derived from propyleneis over 85% and 100% or less

[η_(Ai)]: intrinsic viscosity (dl/g) of component (A-i)

m_(Ai): weight ratio (%) of component (A-i)

The component (A), includes a propylene polymer mixture containing apolymer (A-1) having an intrinsic viscosity of over 0.7 dl/g and 1.1dl/g or less and a polymer (A-2) having an intrinsic viscosity of over1.1 dl/g and 10 dl/g or less wherein the intrinsic viscosity of themixture is 1.05 dl/g or more.

The melting temperature of the component (A) is usually 100° C. or more.When the component (A) is a propylene homopolymer or a polymer derivedfrom a heterophasic propylene polymerization material described later,the melting temperature of the component (A) is preferably 155° C. ormore, more preferably 160° C. or more. When the component (A) is apropylene random copolymer, the melting temperature of the component (A)is preferably 130° C. or more, more preferably 135° C. or more. Themelting temperature of the component (A) is usually 175° C. or less.

The melt flow rate of the component (A) measured by method B underconditions of a temperature of 230° C. and a load of 21.18 N accordingto a method prescribed in JIS K-7210 is preferably 10 g/10 min or moreand 300 g/10 min or less, more preferably 20 g/10 min or more and 200g/10 min or less, for obtaining better impact strength at lowtemperature of a molded body.

The content of the component (A) is 26% by weight or more and 59% byweight or less when the total amount of the component (A), the component(B), the component (C) and the component (D) contained in thethermoplastic elastomer composition is 100% by weight, and it ispreferably 31% by weight or more and 53% by weight or less, morepreferably 36% by weight or more and 49% by weight or less, from thestandpoint of rigidity at high temperature of a molded body.

<Component (B)>

The component (B)) is a copolymer having a monomer unit derived fromethylene and a monomer unit derived from at least one selected from thegroup consisting of propylene and α-olefins having a number of carbonatoms of 4 or more and 12 or less in which the content of a monomer unitderived from ethylene is 15% or more and less than 60% when the totalamount of a monomer unit derived from ethylene and a monomer unitderived from at least one selected from the group consisting ofpropylene and α-olefins having a number of carbon atoms of 4 or more and12 or less contained in the copolymer is 100%, and the intrinsicviscosity ([RB]) is 5.5 dl/g or more.

The component (B) may contain two or more kinds of monomer units derivedfrom at least one selected from the group consisting of propylene andα-olefins having a number of carbon atoms of 4 or more and 12 or less.

The α-olefin having a number of carbon atoms of 4 or more and 12 or lessincludes 1-butene, 2-methylpropylene, 1-pentene, 3-methyl-1-butene,1-hexene, 4-methyl-1-pentene, and 1-octene. The α-olefin having a numberof carbon atoms of 4 or more and 12 or less is preferably 1-hexene or1-octene.

The component (B) includes an ethylene-propylene copolymer, anethylene-1-butene copolymer, an ethylene-propylene-1-butene copolymer,an ethylene-1-hexene copolymer, an ethylene-1-octene copolymer, anethylene-1-hexene-1-octene copolymer, an ethylene-propylene-1-butenecopolymer, an ethylene-propylene-1-hexene copolymer, anethylene-propylene-1-octene copolymer, and an ethylene-1-butene-1-octenecopolymer, and an ethylene-propylene copolymer is preferable. Thecomponent (B) may be a random copolymer or may be a block copolymer. Theblock copolymer as the component (B) includes an olefin-based blockcopolymer containing a polymerization block comprising ethylene and anethylene-α-olefin copolymerization block.

In the component (B), the number of a monomer unit derived from ethyleneis 15% or more and less than 60%, preferably 22% or more and less than58%, more preferably 36% or more and less than 53% when the total numberof all monomer units contained in the copolymer is 100%.

The number of a monomer unit derived from ethylene in the component (B)can be determined by a method prescribed in ASTM D 3900.

The component (B) may also contain a monomer unit derived from anon-conjugated diene. The non-conjugated diene includes chainnon-conjugated dienes such as 1,4-hexadiene, 1,6-octadiene,2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, and7-methyl-1,6-octadiene; cyclic non-conjugated dienes such ascyclohexadiene, dicyclopentadiene, methyltetrahydroindene,5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene,5-isopropylidene-2-norbornene, and6-chloromethyl-5-isopropenyl-2-norbornene; trienes such as2,3-diisopropylidene-5-norbornene,2-ethylidene-3-isopropylidene-5-norbornene,2-propenyl-2,2-norbornadiene, 1,3,7-octatriene, and 1,4,9-decatriene,and preferable is 5-ethylidene-2-norbornene, 5-vinylnorbornene ordicyclopentadiene. The component (B) may have two or more kinds of themonomer units derived from a non-conjugated diene.

When the component (B) contains a monomer unit derived from anon-conjugated diene, the iodine value of the component (B) is 0.1 ormore and 20 or less, and it is preferably 0.1 or more and 15 or less,more preferably 0.1 or more and 5 or less, from the standpoint ofrigidity of a molded body.

In the present specification, “iodine value” denotes a number (unit:none) represented in terms of “g” of the mass of iodine reacting with100 g of a copolymer comprising a monomer unit derived from anon-conjugated diene. The iodine value of a copolymer comprising amonomer unit derived from a non-conjugated diene is determined byinfrared spectroscopy.

The component (B) can be obtained by copolymerizing ethylene and atleast one selected from the group consisting of propylene and α-olefinshaving a number of carbon atoms of 4 or more and 12 or less, in thepresence of a catalyst for olefin polymerization. The catalyst forolefin polymerization includes complex type catalysts such as aZiegler-Natta type catalyst, a metallocene type catalyst, and anon-metallocene type catalyst. The polymerization method includes aslurry polymerization method, a solution polymerization method, a bulkpolymerization method, and a gas phase polymerization method.

The intrinsic viscosity ([rB]) of the component (B) is preferably 5.5dl/g or more and 12.0 dl/g or less, more preferably 5.8 dl/g or more and10.0 dl/g or less, from the standpoint of welding strength to a moldedbody comprising a propylene-based polymer.

The thermoplastic elastomer composition according to the presentinvention may contain only one kind of the component (B) or may containtwo or more kinds of the component (B). When the thermoplastic elastomercomposition contains two or more kinds of the component (B) and [nB]obtained by substituting the intrinsic viscosity of each component (B)into the formula (2) is 5.5 dl/g or more, a mixture of the two or morekinds of the component (B) is “component (B)”.[ηB]=Σ([η_(Bi)]×m _(Bi))/Σ[m _(Bi)]  (2)

Component (B-i): a copolymer comprising a monomer unit derived fromethylene in which the number of the monomer unit derived from ethyleneis 15% or more and less than 60%

[η_(Bi)]: intrinsic viscosity (dl/g) of component (B-i)

m_(Bi): weight ratio (%) of component (B-i)

The content of the component (B) is 2% by weight or more and 9% byweight or less when the total amount of the component (A), the component(B), the component (C) and the component (D) contained in thethermoplastic elastomer composition is 100% by weight, and it ispreferably 4% by weight or more and 8% by weight or less, morepreferably 5% by weight or more and 8% by weight or less, from thestandpoint of rigidity at high temperature of a molded body.

The component (A) and the component (B) contained in the thermoplasticelastomer composition may be a polymer derived from a heterophasicpropylene polymerization material comprising the component (A) and thecomponent (B).

In the present specification, “heterophasic propylene polymerizationmaterial” denotes a mixture having a structure in which anethylene-based copolymer is dispersed in a matrix of a propylene-basedpolymer.

The content of the component (A) contained in a heterophasic propylenepolymerization material comprising the component (A) and the component(B) is preferably 60% by weight or more and 95% by weight or less, andthe content of the component (B) is preferably 5% by weight or more and40% by weight or less when the total amount of the heterophasicpropylene polymerization material is 100% by weight. From the standpointof impact strength at low temperature of a molded body, the content ofthe component (A) is preferably 75% by weight or more and 90% by weightor less, and the content of the component (B) is preferably 10% byweight or more and 25% by weight or less when the total amount of theheterophasic propylene polymerization material is 100% by weight. Thecomponent (A) of the heterophasic propylene polymerization material maybe contained only singly or two or more kinds of the components (A) maybe contained. The component (B) of the heterophasic propylenepolymerization material may be contained only singly or two or morekinds of the components (B) may be contained.

The heterophasic propylene polymerization material can be produced bymulti-stage polymerization in the presence of a polymerization catalyst.In a first polymerization step, a monomer containing propylene ispolymerized in the presence of a polymerization catalyst to produce acomponent (A), and in a second polymerization step, at least one monomerselected from the group consisting of propylene and α-olefins having anumber of carbon atoms of 4 or more and 12 or less and ethylene arecopolymerized in the presence of the component (A) obtained in the firstpolymerization step to produce a component (B), thereby the heterophasicpropylene polymerization material can be produced.

The polymerization catalyst used for producing a propylenepolymerization material includes a Ziegler type catalyst system, aZiegler-Natta type catalyst system, a catalyst system comprising acompound of a transition metal belonging to group 4 of the periodictable having a cyclopentadienyl ring and an alkylaluminoxane, a catalystsystem comprising a compound of a transition metal belonging to group 4of the periodic table having a cyclopentadienyl group, a compoundreacting with the transition metal compound to form an ionic complex andan organoaluminum compound.

A pre-polymerization catalyst may be used in the presence of thepolymerization catalyst. The pre-polymerization catalyst includescatalyst systems described in JP-A No. Sho-61-218606, JP-A No.Sho-61-287904, JP-A No. Hei-5-194685, JP-A No. Hei-7-216017, JP-A No.Hei-9-316147, JP-A No. Hei-10-212319 and JP-A No. 2004-182981.

The polymerization process for producing the propylene polymerizationmaterial incudes bulk polymerization, solution polymerization, slurrypolymerization and gas phase polymerization. The inactive hydrocarbonsolvent used in solution polymerization and slurry polymerizationincludes propane, butane, isobutane, pentane, hexane, heptane andoctane. Two or more of these polymerization processes may be combined,and the polymerization process may be any of batch mode or continuousmode. As the polymerization process for producing the propylenepolymerization material, continuous mode gas phase polymerization andbulk-gas phase polymerization performing bulk polymerization and gasphase polymerization continuously are preferable.

In the heterophasic propylene polymerization material, the [ηA] may bethe following [ηcxis], and the [ηB] may be the following [ηcxs]. Theintrinsic viscosity ([ηcxs]) of the 20° C. xylene-soluble portion (CXSportion) is preferably 5.5 dl/g or more and 12.0 dl/g or less, morepreferably 5.8 dl/g or more and 10.0 dl/g or less, from the standpointof welding strength to a molded body comprising propylene-based polymer.The ratio of [ηcxs] to the intrinsic viscosity ([ηcxis]) of the 20° C.xylene-insoluble portion (CXIS portion) is preferably 1.8 or more and 9or less.

The CXS portion and the CXIS portion are obtained by the followingmethod. About 5 g of a propylene polymerization material is dissolvedcompletely in 500 ml of boiling xylene, then, the resultant xylenesolution is gradually cooled down to room temperature, and kept at 20°C. for 4 hours or more, and the precipitate and the solution areobtained by filtration. The resultant precipitate is the CXIS portion.The product obtained by removing the solvent from the resultant solutionis the CXS portion.

The melt flow rate of a heterophasic propylene polymerization materialmeasured by method B under conditions of a temperature of 230° C. and aload of 21.18 N according to a method prescribed in JIS K-7210 ispreferably 10 g/10 min or more and 200 g/10 min or less, more preferably15 g/10 min or more and 100 g/10 min or less, from the standpoint ofimpact strength at low temperature of a molded body.

The total content of the component (A) and the component (B) in athermoplastic elastomer composition is 30% by weight or more and 68% byweight or less, preferably 41% by weight or more and 61% by weight orless, more preferably 46% by weight or more and 54% by weight or lesswhen the sum of the contents of the component (A), the component (B),the component (C) and the component (D) is 100% by weight, from thestandpoint of rigidity at high temperature and impact strength at lowtemperature of a molded body and welding strength to a molded bodycomprising a propylene-based polymer.

<Component (C)>

The component (C) is a copolymer having a monomer unit derived fromethylene and a monomer unit derived from at least one selected from thegroup consisting of α-olefins having a number of carbon atoms of 5 ormore and 12 or less in which the number of a monomer unit derived fromethylene is 83% or more and less than 93% when the total number of allmonomer units contained in the copolymer is 100%.

The component (C) may have two or more kinds of monomer units derivedfrom at least one selected from the group consisting of α-olefins havinga number of carbon atoms of 5 or more and 12 or less. The thermoplasticelastomer composition according to the present invention may containonly one kind of the component (C) or may contain two or more kinds ofthe components (C).

The α-olefin having a number of carbon atoms of 5 or more and 12 or lessin the component (C) includes 1-pentene, 3-methyl-1-butene, 1-hexene,4-methyl-1-pentene, and 1-octene. The α-olefin having a number of carbonatoms of 5 or more and 12 or less is more preferably 1-hexene or1-octene.

The component (C) includes an ethylene-1-hexene copolymer, anethylene-1-octene copolymer, and an ethylene-1-hexene-1-octenecopolymer. The component (C) may be a random copolymer or may be a blockcopolymer. The block copolymer as the component (C) includes anolefin-based block copolymer containing a polymerization blockcomprising ethylene and an ethylene-α-olefin copolymerization block.

The number of a monomer unit derived from ethylene in the component (C)is 83% or more and less than 93%, preferably 86% or more and less than92% when the total number of all monomer units contained in thecopolymer is 100%.

The number of a monomer unit derived from ethylene in the component (C)can be determined by ¹³C-nuclear magnetic resonance spectroscopy.

The component (C) may contain a monomer unit derived from anon-conjugated diene. The non-conjugated diene in the monomer unitderived from a non-conjugated diene includes non-conjugated dieneslisted as the non-conjugated diene in the component (B).

When the component (C) contains a monomer unit derived from anon-conjugated diene, the iodine value of the component (C) is 0.1 ormore and 20 or less, and it is preferably 0.1 or more and 15 or less,more preferably 0.1 or more and 5 or less, from the standpoint ofrigidity of a molded body.

The component (C) can be obtained by copolymerizing ethylene and atleast one selected from the group consisting of α-olefins having anumber of carbon atoms of 5 or more and 12 or less in the presence of acatalyst for olefin polymerization. The catalyst for olefinpolymerization includes complex type catalysts such as a Ziegler-Nattatype catalyst, a metallocene type complex, and a non-metallocene typecomplex. The polymerization method includes a slurry polymerizationmethod, a solution polymerization method, a bulk polymerization method,and a gas phase polymerization method.

The intrinsic viscosity ([nC]) of the component (C) is preferably 0.5dl/g or more and less than 5.5 dl/g, more preferably 0.7 dl/g or moreand 3.5 dl/g or less, further preferably 0.8 dl/g or more and 2.5 dl/gor less, from the standpoint of welding strength to a molded bodycomprising a propylene-based polymer. When the thermoplastic elastomercomposition contains two or more kinds of component (C), [ηC] determinedby substituting the intrinsic viscosity of each component (C) into theformula (3) is the intrinsic viscosity of the component (C).[ηC]=Σ([η_(Ci)]×m _(Ci))/Σ[m _(Ci)]  (3)

Component (C-i): an copolymer comprising a monomer unit derived fromethylene in which the content of the monomer unit derived from ethyleneis 83% or more and less than 93%

[ηci]: intrinsic viscosity (dl/g) of component (C-i)

m_(Ci): weight ratio (%) of component (C-i)

The melting temperature of the component (C) is preferably 50° C. ormore and 130° C. or less, more preferably 53° C. or more and 120° C. orless, more preferably 55° C. or more and 90° C. or less.

The density of the component (C) is preferably 0.865 g/cm³ or more andless than 0.875 g/cm³, more preferably 0.868 g/cm³ or more and 0.872g/cm³ or less, from the standpoint of further improvement of impactstrength at low temperature of a molded body comprising a thermoplasticelastomer composition and from the standpoint of welding strength to amolded body comprising a propylene-based polymer.

In the present specification, the density is measured according to amethod prescribed in JIS K7112 without annealing.

The melt flow rate of the component (C) measured by method B underconditions of a temperature of 190° C. and a load of 21.18 N accordingto a method prescribed in JIS K-7210 is preferably 0.01 g/10 min or moreand 2 g/10 min or less, more preferably 0.05 g/10 min or more and 1.5g/10 min or less, further preferably 0.1 g/10 min or more and 1.2 g/10min or less, from the standpoint of welding strength to a molded bodycomprising a propylene-based polymer.

The content of the component (C) is 16% by weight or more and 61% byweight or less when the total amount of the component (A), the component(B), the component (C) and the component (D) contained in thethermoplastic elastomer composition is 100% by weight, and it ispreferably 24% by weight or more and 39% by weight or less, morepreferably 27% by weight or more and 36% by weight or less, from thestandpoint of rigidity at high temperature of a molded body and weldingstrength to a molded body comprising a propylene-based polymer.

<Component (D)>

The component (D) is a copolymer having a monomer unit derived fromethylene in which the number of a monomer unit derived from ethylene is60% or more and less than 83% when the total number of all monomer unitscontained in the copolymer is 100% and a monomer unit derived from atleast one selected from the group consisting of propylene and α-olefinshaving a number of carbon atoms of 4 or more and 12 or less.

The component (D) may have two or more kinds of monomer units derivedfrom at least one selected from the group consisting of propylene andα-olefins having a number of carbon atoms of 4 or more and 12 or less.The thermoplastic elastomer composition according to the presentinvention may contain only one kind of the component (D) or may containtwo or more kinds of the components (D).

The α-olefin having a number of carbon atoms of 4 or more and 12 or lessin the component (D) includes 1-butene, 2-methylpropene, 1-pentene,3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. Theα-olefin having a number of carbon atoms of 4 or more and 12 or less ismore preferably 1-butene.

The component (D) includes an ethylene-propylene copolymer, anethylene-1-butene copolymer, an ethylene-propylene-1-butene copolymer,an ethylene-1-hexene copolymer, an ethylene-1-octene copolymer, anethylene-1-hexene-1-octene copolymer, an ethylene-propylene-1-hexenecopolymer, an ethylene-propylene-1-octene copolymer, and anethylene-1-butene-1-octene copolymer. The component (D) may be a randomcopolymer or may be a block copolymer. The block copolymer as thecomponent (D) includes an olefin-based block copolymer containing apolymer block comprising ethylene and an ethylene-α-olefincopolymerization block.

The number of a monomer unit derived from ethylene in the component (D)is 60% or more and less than 83%, preferably 71% or more and less than80% when the total number of all monomer units contained in thecopolymer is 100%.

The number of a monomer unit derived from ethylene in the component (D)can be determined by ¹³C-nuclear magnetic resonance spectroscopy.

The component (D) may contain a monomer unit derived from anon-conjugated diene. The non-conjugated diene in the monomer unitderived from a non-conjugated diene in the component (D) includesnon-conjugated dienes listed as the non-conjugated diene in thecomponent (B).

When the component (D) contains a monomer unit derived from anon-conjugated diene, the iodine value of the component (D) is 0.1 ormore and 20 or less, and it is preferably 0.1 or more and 15 or less,more preferably 0.1 or more and 10 or less, from the standpoint ofrigidity of a molded body.

The component (D) can be obtained by copolymerizing ethylene and atleast one selected from the group consisting of α-olefins having anumber of carbon atoms of 5 or more and 12 or less in the presence of acatalyst for olefin polymerization. The catalyst for olefinpolymerization includes complex type catalysts such as a Ziegler-Nattatype catalyst, a metallocene type complex, and a non-metallocene typecomplex. The polymerization method includes a slurry polymerizationmethod, a solution polymerization method, a bulk polymerization method,and a gas phase polymerization method.

The intrinsic viscosity ([ηD]) of the component (D) is preferably 0.5dl/g or more and less than 5.5 dl/g, more preferably 0.7 dl/g or moreand 3.5 dl/g or less, further preferably 0.8 dl/g or more and 3.0 dl/gor less, from the standpoint of impact strength at low temperature of amolded body. When the thermoplastic elastomer composition contains twoor more kinds of the component (D), [ηD] determined by substituting theintrinsic viscosity of each component (D) into the formula (4) is theintrinsic viscosity of the component (D).[ηD]=Σ([η_(Di)]×m _(Di))/Σ[m _(Di)]  (4)

Component (D-i): a copolymer comprising a monomer unit derived fromethylene in which the content of the monomer unit derived from ethyleneis 60% or more and less than 83%

[η_(Di)]: intrinsic viscosity (dl/g) of component (D-i)

m_(Di): weight ratio (%) of component (D-i)

The melting temperature of the component (D) is preferably less than 50°C., and it is more preferably less than 48° C., further preferably lessthan 40° C., from the standpoint of impact strength at low temperatureof a molded body.

The density of the component (D) is preferably 0.850 g/cm³ or more andless than 0.865 g/cm³, more preferably 0.852 g/cm³ or more and 0.862g/cm³ or less, from the standpoint of impact strength at low temperatureof a molded body comprising a thermoplastic elastomer composition andwelding strength to a molded body comprising a propylene-based polymer.

The melt flow rate of the component (D) measured by method B underconditions of a temperature of 190° C. and a load of 21.18 N accordingto a method prescribed in JIS K-7210 is preferably 0.01 g/10 min or moreand 0.7 g/10 min or less, more preferably 0.05 g/10 min or more and 0.5g/10 min or less, further preferably 0.1 g/10 min or more and 0.3 g/10min or less, from the standpoint of welding strength to a molded bodycomprising a propylene-based polymer.

The content of the component (D) is 11% by weight or more and 56% byweight or less when the total amount of the component (A), the component(B), the component (C) and the component (D) contained in thethermoplastic elastomer composition is 100% by weight, and it ispreferably 14% by weight or more and 40% by weight or less, morepreferably 17% by weight or more and 25% by weight or less, from thestandpoint of rigidity at high temperature and welding strength to amolded body comprising a propylene-based polymer.

The ratio of the content of the component (C) to the content of thecomponent (D) (component (C) (% by weight)/component (D) (% by weight))is over 1 and 5 or less, and it is preferably 1.1 or more and 3.4 orless, more preferably 1.2 or more and 1.9 or less, from the standpointof impact strength at low temperature of a molded body and weldingstrength to a molded body comprising a propylene-based polymer.

The total amount of the component (A), the component (B), the component(C) and the component (D) is preferably 86% or more when the totalamount of the thermoplastic elastomer composition of the presentinvention is 100% by weight.

<Other Component>

The thermoplastic elastomer composition of the present invention mayfurther contain a fatty acid having a number of carbon atoms of 5 ormore, a metal salt of a fatty acid having a number of carbon atoms of 5or more, an amide compound of a fatty acid having a number of carbonatoms of 5 or more or an ester compound of a fatty acid having a numberof carbon atoms of 5 or more, and these compounds may be contained eachsingly or two or more kinds of the compounds may be contained.

The fatty acid having a number of carbon atoms of 5 or more includeslauric acid, palmitic acid, stearic acid, behenic acid, oleic acid,erucic acid, linoleic acid, and ricinoleic acid.

The metal salt of a fatty acid having a number of carbon atoms of 5 ormore is a metal salt of the fatty acid having a number of carbon atomsof 5 or more. The metal includes Li, Na, Mg, Al, K, Ca, Zn, Ba, and Pb.The metal salt of a fatty acid having a number of carbon atoms of 5 ormore includes lithium stearate, sodium stearate, calcium stearate, andzinc stearate.

The amide compound of a fatty acid having a number of carbon atoms of 5or more includes lauric amide, palmitic amide, stearic amide, oleicamide, erucamide, methylenebisstearic amide, ethylenebisstearic amide,ethylenebisoleic amide, and stearyldiethanolamide, and erucamide ispreferable.

The ester compound of a fatty acid having a number of carbon atoms of 5or more includes esters comprising an alcohol and the fatty acid havinga number of carbon atoms of 5 or more.

The alcohol includes aliphatic alcohols such as myristyl alcohol,palmityl alcohol, stearyl alcohol, behenyl alcohol, and 12-hydroxystearyl alcohol; aromatic alcohols such as benzyl alcohol, β-phenylethylalcohol, and phthalyl alcohol; polyhydric alcohols such as glycerin,diglycerin, polyglycerin, sorbitan, sorbitol, propylene glycol,polypropylene glycol, polyethylene glycol, pentaerythritol, andtrimethylolpropane.

The ester of a fatty acid having a number of carbon atoms of 5 or moreincludes glycerin monooleate, glycerin dioleate, polyethylene glycolmonostearate, and citric acid distearate.

The contents of the fatty acid having a number of carbon atoms of 5 ormore, the metal salt of a fatty acid having a number of carbon atoms of5 or more, the amide compound of a fatty acid having a number of carbonatoms of 5 or more or the ester compound of a fatty acid having a numberof carbon atoms of 5 or more are each preferably 0.01 parts by weight ormore and 1.5 parts by weight or less, more preferably 0.05 parts byweight or more and 1.0 parts by weight or less when the sum of thecontents of the component (A), the component (B), the component (C) andthe component (D) is 100 parts by weight.

The thermoplastic elastomer composition according to the presentinvention may appropriately contain resins other than the component (A),the component (B), the component (C) and the component (D); inorganicfillers such as talc, calcium carbonate, fired kaolin, glass fiber,hollow glass sphere, silica, metal soap, titanium dioxide, mica, andpotassium titanate fiber; organic fillers such asfiber, wood flour,cellulose powder, carbon fiber, and carbon black; lubricants such assilicone oil, and silicone rubber; antioxidants such as phenol type,sulfur-based, phosphorus-based, lactone type, and vitamin-based;weather-resistant stabilizers; ultraviolet absorbers such asbenzotriazole type, triazine type, anilide type, and benzophenone type;heat stabilizers; light stabilizers such as hindered amine type, andbenzoate type; pigments; nucleating agents; adsorbents which are metaloxides such as zinc oxide, and magnesium oxide, metal chlorides such asiron chloride, and calcium chloride, hydrotalcite, and aluminate;softeners; cross-linking agents such as organic peroxide; andcross-linking aids such as trimethylolpropane trimethacrylate,N,N-m-phenylene bismaleimide, and divinylbenzene.

The resin other than the component (A), the component (B), the component(C) and the component (D) includes olefin-based resins excluding thosecorresponding to the component (A), the component (B), the component (C)or the component (D); olefin-based elastomers excluding thosecorresponding to the component (A), the component (B), the component (C)or the component (D); styrene-based elastomers, polyphenyleneether-based resins, polyamide-based resins, polyester-based resins,polyoxymethylene-based resins, and polymethyl methacrylate-based resins.

The olefin-based elastomer includes copolymers comprising a monomer unitderived from ethylene and a monomer unit derived from at least oneselected from the group consisting of propylene and α-olefins having anumber of carbon atoms of 4 or more and 12 or less.

The copolymer comprising a monomer unit derived from ethylene and amonomer unit derived from at least one selected from the groupconsisting of propylene and α-olefins having a number of carbon atoms of4 or more and 12 or less includes a propylene-ethylene copolymer, anethylene-1-butene copolymer, a propylene-ethylene-1-butene copolymer, anethylene-1-hexene copolymer, an ethylene-1-octene copolymer, anethylene-1-hexene-1-octene copolymer, a propylene-ethylene-1-hexenecopolymer, a propylene-ethylene-1-octene copolymer, and anethylene-1-butene-1-octene copolymer, and preferable are apropylene-ethylene copolymer or an ethylene-1-octene copolymer, apropylene-ethylene-1-butene copolymer, a propylene-ethylene-1-hexenecopolymer, a propylene-ethylene-1-octene copolymer and anethylene-1-butene-1-octene copolymer. The copolymer comprising a monomerunit derived from ethylene and a monomer unit derived from at least oneselected from the group consisting of propylene and α-olefins having anumber of carbon atoms of 4 or more and 12 or less may be a randomcopolymer or may be a block copolymer. The block copolymer includes anolefin-based block copolymer containing a polymerization blockcomprising ethylene and an ethylene-α-olefin copolymerization block.

The styrene-based elastomer includes a hydrogenated product of astyrene-butadiene block copolymer (styrene-(ethylene/butylene)-styrenecopolymer).

The softener includes mineral oils such as paraffinic mineral oils,naphthenic mineral oils and aromatic mineral oils, and paraffinicmineral oils are preferable. The softener may be added in melt-kneadingthe component (A), the component (B), the component (C) and thecomponent (D), alternatively, the softener may be previously mixed withany component before melt kneading. The process for mixing anethylene-based copolymer and the softener include a process for mixingan ethylene-based copolymer in the form of solid with the softener witha mixing machine, and a process for mixing a solution of anethylene-based copolymer with the softener to obtain a mixture, then,removing a solvent in the mixture.

The content of the softener is preferably 0.1% by weight or more and 15%by weight or less when the total amount of the thermoplastic elastomercomposition is 100% by weight.

In the present specification, “mineral oil” denotes a substance which isliquid or grease at normal temperature and which comprises at least onecompound selected from the group consisting of aromatic compounds,naphthene ring compounds and paraffinic compounds obtained frompetroleum-derived hydrocarbon compounds.

The thermoplastic elastomer composition may be produced bysimultaneously melt-kneading all components contained in thecomposition, or a process for producing the thermoplastic elastomercomposition may comprise a step of melt-kneading a part of components ofthe thermoplastic elastomer composition to obtain a composition (A) anda step of adding residual components of the thermoplastic elastomercomposition to the composition (A) and melt-kneading them. Melt keadingmay be conducted in two or more divided processes.

The process for producing the thermoplastic elastomer compositionincludes a process for the thermoplastic elastomer compositioncomprising a step of melt-kneading the component (A), the component (B),the component (C) and the component (D).

Components other than the component (A), the component (B), thecomponent (C) and the component (D) may be added in the step ofmelt-kneading.

The melt kneading apparatus used for the melt kneading includes a mixingroll as an open apparatus, and a Bunbury mixer, an extruder, a kneaderand a continuous mixer as a closed apparatus. In the present invention,a closed apparatus is preferably used. The temperature in melt kneadingis usually 150° C. or more and 250° C. or less, and the melt kneadingtime is usually 10 seconds or more and 30 minutes or less.

The molded body comprising the thermoplastic elastomer compositionincludes automobile interior parts, automobile exterior parts, electricparts, home electronics parts, furniture parts, footwear members, andarchitectural members. The automobile interior parts include an airbagcover, an instrumental panel, and a pillar, and the automobile exteriorparts include a side molding.

The molding method of a molded body comprising the thermoplasticelastomer composition is preferably an injection molding method. Whenthe thermoplastic elastomer composition is injection-molded, the moldingtemperature in injection molding is usually 150° C. or more and 300° C.or less, preferably 180° C. or more and 280° C. or less, more preferably200° C. or more and 250° C. or less. The temperature of a metal moldused in injection molding is usually 0° C. or more and 100° C. or less,preferably 20° C. or more and 90° C. or less, more preferably 40° C. ormore and 80° C. or less, further preferably 50° C. or more and 75° C. orless.

[Physical Property of Thermoplastic Elastomer Composition and MoldedBody]

It is preferable for the thermoplastic elastomer composition that thebending elastic modulus measured at a temperature of 90° C. according toa method prescribed in JIS K7203 of a molded body obtained by moldingthe thermoplastic elastomer composition by the following method is 100MPa or more and 140 MPa or less.

Molding method of molded body: a thermoplastic elastomer composition isinjection-molded by an injection molding machine equipped with a sidegate flat sheet metal mold (length 90 mm, width 150 mm, thickness 2 mm)under conditions of a cylinder temperature of 220° C. and a moldtemperature of 50° C., to obtain an injection-molded body having alength of 90 mm, a width of 150 mm and a thickness of 2 mm.

The bending elastic modulus measured at a temperature of 90° C.according to a method prescribed in JIS K7203 of the molded bodycomprising the thermoplastic elastomer composition is preferably 100 MPaor more and 140 MPa or less.

Izod impact strength of the molded body at −45° C. is measured accordingto JIS K7110. The evaluation of Izod impact strength of the molded bodyis preferably no break.

A first molded body comprising a propylene-based polymer and a secondmolded body comprising the thermoplastic elastomer composition accordingto the present invention can be welded with each other, to obtain acomposite molded body.

As the method for welding, a vibration welding method is mentioned.

The propylene-based polymer constituting the first molded body includesa propylene homopolymer, a propylene random copolymer and a heterophasicpropylene polymerization material.

The propylene random copolymer includes

(1) a propylene-ethylene random copolymer in which the number of amonomer unit derived from propylene is over 85% and 99.2% or less andthe number of a monomer unit derived from ethylene is 0.8% or more andless than 15% when the total number of a monomer unit derived frompropylene and a monomer unit derived from ethylene is 100%;

(2) a propylene-ethylene-α-olefin random copolymer in which the numberof a monomer unit derived from propylene is over 85% and 98.5% or less,the number of a monomer unit derived from ethylene is 0.15% or more andless than 15% and the number of a monomer unit derived from an α-olefinhaving a number of carbon atoms of 4 or more and 12 or less is 0.03% ormore and less than 15% when the total number of a monomer unit derivedfrom propylene, a monomer unit derived from ethylene and a monomer unitderived from an α-olefin having a number of carbon atoms of 4 or moreand 12 or less is 100%; or

(3) a propylene-α-olefin random copolymer in which the number of amonomer unit derived from propylene is 92.5% or more and 99.8% or lessand the number of a monomer unit derived from an α-olefin having anumber of carbon atoms of 4 or more and 12 or less is 0.2% or more and7.5% or less when the total number of a monomer unit derived frompropylene and a monomer unit derived from an α-olefin having a number ofcarbon atoms of 4 or more and 12 or less is 100%.

The heterophasic propylene polymerization material includes aheterophasic propylene polymerization material comprising apropylene-based polymer and an ethylene-based copolymer. The content ofthe ethylene-based copolymer contained in the heterophasic propylenepolymerization material is preferably 10% by weight or more and 40% byweight or less when the total amount of the heterophasic propylenepolymerization material is 100% by weight.

The melt flow rate of a propylene-based polymer constituting the firstmolded body (i) measured by method B under conditions of a temperatureof 230° C. and a load of 21.18 N according to a method prescribed in JISK-7210 is preferably 25 g/10 min or more and 100 g/10 min or less.

In the composite molded body, welding strength between the first moldedbody comprising a propylene-based polymer and the second molded bodycomprisingthe thermoplastic elastomer composition is preferably 7.8 MPaor more, more preferably 8.0 MPa or more.

In a composite molded body in which the first molded body comprising apropylene-based polymer and the second molded body comprising thethermoplastic elastomer composition are welded with each other,

when the cross-sectional surface perpendicular to the welding surface isstained with a vapor of ruthenium tetraoxide, the stained domainpreferably satisfies the requirement (1), and further, more preferablysatisfies the requirement (2).

Requirement (1): when the stained cross-sectional surface is observedwith a transmission electron microscope, D7 is 115 nm or less, whereinD7 is the number-average circle-equivalent diameter of the staineddomain in a square having a side of 4 μm around a point where thedistance from the welded part is 7 μm in a vertical direction, whereinthe square presents in the second molded body.

Requirement (2): when the stained cross-sectional surface is observedwith a transmission electron microscope, D200/D7 is 3.5 or more, whereinD200 is the number-average circle-equivalent diameter of the staineddomain in a square having a side of 4 μm around a point where thedistance from the welded part is 200 μm in a vertical direction, whereinthe square present in the second molded body. When the cross-sectionalsurface perpendicular to the welding surface is stained with a vapor ofruthenium tetraoxide, the stained domain is supposed to be a domaincomprising an ethylene-based copolymer. In a composite molded body inwhich the stained domain satisfies the requirement (1), welding strengthbetween the first molded body and the second molded body is guessed tobe high.

D7 and D200/D7 can be controlled by adjusting the [nB] and the ratio ofthe content of the component (C) to the content of the component (D).

EXAMPLES

[Measurement of Physical Property]

1. Intrinsic viscosity ([ηA], [ηB], [ηC], [ηD], [ηcxs], [ηcxis], unit:dl/g)

The reduced viscosity of each components was measured using a Ubbelohdetype viscometer in tetralin at 135° C., and each intrinsic viscositythereof was determined by an extrapolation method according to acalculation method described in “Polymer Solution, Polymer Experiment(Kobunshi Jikkengaku) 11” (published by Kyoritsu Shuppan Co., Ltd.,1982) p. 491.

For the heterophasic propylene polymerization material in the presentexamples,

the intrinsic viscosity ([rcxis]) of the 20° C. xylene-insoluble portionis regarded as the intrinsic viscosity ([HA]) of the propylenehomopolymer component contained in the heterophasic propylenepolymerization material,

and the intrinsic viscosity ([ncxs]) of the 20° C. xylene-solubleportion is regarded as the intrinsic viscosity ([RB]) of theethylene-propylene copolymer component contained in the heterophasicpropylene polymerization material.

2. Melting Temperature (Unit: ° C.)

The peak temperature which is the peak temperature of the highestendotherm peak among endothermic peaks in the melting curve measured bythe following differential scanning calorimetry is the meltingtemperature.

<Condition of Differential Scanning Calorimetry>

Using a differential scanning calorimeter, an aluminum pan having about5 mg of an enclosed sample is (1) kept at 220° C. for 5 minutes, then,(2) cooled from 220° C. to −90° C. at a rate of 5° C./min, then, (3)heated from −90° C. to 200° C. at a rate of 5° C./min, under a nitrogenatmosphere. The differential scanning calorimetry curve obtained bycalorimetry in step (3) is the melting curve.

3. Density (Unit: g/Cm³⁾

The density was measured according to a method prescribed in JIS K7112without annealing.

4. Melt Flow Rate (Unit: g/10 Min)

The melt flow raw was measured by method B under conditions of atemperature of 230° C. or 190° C. and a load of 21.18 N according to amethod prescribed in JIS K-7210. Hereinafter, the melt flow ratemeasured by method B under conditions of a temperature of 230° C. and aload of 21.18 N is written as “MFR (230° C.)”. The melt flow ratemeasured by method B under conditions of a temperature of 190° C. and aload of 21.18 N is written as “MFR (190° C.)”.

5. Number of monomer unit derived from ethylene and number of monomerunit derived from at least one selected from the group consisting ofpropylene and α-olefins having a number of carbon atoms of 4 or morecontained in component (A) or component (B)

The number of a monomer unit derived from ethylene and the number of amonomer unit derived from at least one selected from the groupconsisting of propylene and α-olefins having a number of carbon atoms of4 or more contained in the component (A) or the component (B) weredetermined from infrared absorption spectrum measured with typeFT-IR5200 manufactured by JASCO Corporation according to a methodprescribed in ASTM D 3900.

6. Number of Monomer Unit Derived from Ethylene Contained in Component(C) or Component (D)

The number of a monomer unit derived from ethylene contained in thecomponent (C) or the component (D) was determined by measuring the¹³C-NMR spectrum by ¹³C-nuclear magnetic resonance spectroscopy underthe following conditions (1) to (7) and using a method described in aliterature (JMS-REV. MACROMOL. CHEM. PHYS., C29, 201-317 (1989)).

-   -   (1) instrument: AvancelIII HD600 manufactured by BRUKER (10 mm        cryoprobe)    -   (2) measurement solvent:        1,1,2,2-tetrachloroethane-d2/1,2-dichlorobenzene (volume ratio:        15/85)    -   (3) measurement temperature: 135° C.    -   (4) measuring method: proton decoupling method    -   (5) pulse width: 45 degree    -   (6) pulse repeating time: 4 seconds    -   (7) chemical shift value standard: tetramethylsilane        7. Iodine Value

The component (D) was molded into a film with a thickness of about 0.5mm by a hot press machine. By an infrared spectrophotometer, theintensities of the peak derived from dicyclopendadiene (absorption peakat 1611 cm-1) and the peak derived from 5-ethylidene-2-norbornene(absorption peak at 1688 cm⁻¹) of the film were measured. The molarcontent of a double bond was determined from the peak intensity, and theiodine value was calculated from the molar content.

8. Production Method of Injection Molded Body

Each thermoplastic elastomer composition of examples and comparativeexamples was injection-molded with an injection molding machine EC160NIImanufactured by Toshiba Machine Co., Ltd. equipped with a side gate flatsheet metal mold having a length of 90 mm, a width of 150 mm, and athickness of 2 mm under conditions of a cylinder temperature of 220° C.and a mold temperature of 50° C., to obtain an injection molded bodyhaving a length of 90 mm, a width of 150 mm and of thickness 2 mm. Underthe same conditions, a propylene-based polymer (Nobrene BZE82G8manufactured by Sumitomo Chemical Co., Ltd., melting temperature=165°C., MFR=36 g/10 min) was injection-molded, to obtain an injection moldedbody of the same shape.

9. Rigidity at High Temperature

According to a method prescribed in JIS K7203, bending elastic modulusof an injection molded body produced by “8. Production method ofinjection molded body” was measured under conditions of a bending rateof 1 mm/min and a measurement temperature of 90° C. using the shape ofthe test piece of JIS No. 3 dumbbell. The higher the bending elasticmodulus is, the better the rigidity at high temperature is.

10. Impact Strength at Low Temperature (Izod Impact Strength)

According to a method prescribed in JIS K7110, Izod impact strength ofan injection molded body produced by “8. Production method of injectionmolded body” was measured at a measurement temperature of −45° C.

The measurement results are described as shown below.

NB=no break

B=broken

11. Welding Strength

An injection molded body comprising a propylene-based polymer was thefirst molded body and an injection molded body comprising athermoplastic elastomer composition was the second molded body. Theinjection molded bodies produced by “8. Production method of injectionmolded body” were cut respectively. The first molded body and the secondmolded body were located shown in FIG. 1. The injection direction of thefirst molded body was parallel to the injection direction of the secondmolded body. The second molded body was vibrated and welded to the firstmolded body under conditions of a pressure of 1 bar, a vibrationamplitude of 1.5 mm, a welding depth of 0.4 mm and a retention time of 5seconds by Vibration Welder (type: MICRO-PPL) manufactured by Branson,to obtain a composite molded body having the configuration shown inFIG. 1. A width of this composition molded body was 90 mm. Thiscomposite molded body was cut into a width of 45 mm, and the firstmolded body was fixed to the seat of a tensile tester (Autographmanufactured by Shimadzu Corp., type: AGS-500D) and the second moldedbody was attached to a load cell jig. A tensile test of the injectionmolded body was conducted under conditions of pulling second molded bodypart at a rate of 200 mm/min to the direction of an arrow shown in FIG.2. The maximum tensile strength in the tensile test was adopted as thewelding strength.

12. Measurement of Number-Average Circle-Equivalent Diameter

The composite molded body obtained in the 11. was epoxy-embedded. Fromthe epoxy-embedded composite molded body, a cross-sectional surfaceperpendicular to the welding surface was cut out using a cryomicrotome,and stained with a vapor of ruthenium tetraoxide. From the stainedcross-sectional surface, an ultrathin section having a thickness ofabout 0.1 μm was cut out using a diamond knife.

The stained domain in a square having a side of 4 μm around a pointwhere the shortest distance from the welded part the first molded bodywith the second molded body is 7 μm in a vertical direction, wherein thesquare presents in the second molded body of the cut-out ultrathinsection, was observed with a transmission electron microscope (JEM-2100Ftransmission electron microscope manufactured by JEOL Ltd.) at amagnification of 10,000-fold. The transmission electronmicroscope-observed image was analyzed by image analysis using an imageanalysis software (A-zou kun manufactured by Asahi Kasei Engineering),and the number-average circle-equivalent diameter (D7) of all thestained domains present on the observed image was determined.

In a similar way, the stained domain in a square having a side of 4 μmaround a point where the distance from the welded part is 200 μm in avertical direction, wherein the square present in the second molded bodyof the cut-out ultrathin section was observed with a transmissionelectron microscope at a magnification of 10,000-fold. The transmissionelectron microscope-observed image was analyzed by image analysis, andthe number-average circle-equivalent diameter (D200) of all the staineddomains present on the observed image was determined.

13. Separation of CXIS Portion and CXS Portion

About 5 g of a sample was dissolved completely in 500 ml of boilingxylene, then, the resultant xylene solution was cooled down gradually toroom temperature, and kept at 20° C. for 4 hours or more, and theprecipitate and the solution were obtained by filtration. Theprecipitate was the CXIS portion, and the product obtained by removingthe solvent from the solution was the CXS portion.

[Raw Material]

((A-1-1)+(B-1)) Nobrene WPX5343 manufactured by Sumitomo Chemical Co.,Ltd. (heterophasic propylene polymerization material comprisingpropylene homopolymer component (A-1-1) and ethylene-propylene copolymercomponent (B-1))

(MFR (230° C.)=60 g/10 min; melting temperature=163° C.; [ηcxs]=6.0dl/g; [ηcxis]=0.9 dl/g)

content of ethylene-propylene copolymer component (B-1)=13% by weight

content of monomer derived from ethylene in ethylene-propylene copolymercomponent (B-1)=41%

((A-1-2)+(B-2)) Nobrene AX564E2 manufactured by Sumitomo Chemical Co.,Ltd. (heterophasic propylene polymerization material comprisingpropylene homopolymer component (A-1-2) and ethylene-propylene copolymercomponent (B-2))

(MFR (230° C.)=55 g/10 min; melting temperature=164° C.; [ηcxs]=2.8dl/g; [ηcxis]=1.1 dl/g)

content of ethylene-propylene copolymer component (B-2)=21% by weight

content of monomer derived from ethylene in ethylene-propylene copolymercomponent (B-2)=47%

(A-2-1) Nobrene@ D101 manufactured by Sumitomo Chemical Co., Ltd.

(MFR (230° C.)=0.5 g/10 min; melting temperature=161° C.; [ηcxis]=3.0dl/g)

content of ethylene monomer=0.4%;

(A-2-2) Nobrene® R101 manufactured by Sumitomo Chemical Co., Ltd.

(MFR (230° C.)=20 g/10 min; melting temperature=162° C.; [ηcxis]=1.3dl/g)

content of ethylene monomer=0%;

(C-1) ethylene-1-octene copolymer

Engage® 8150 manufactured by The Dow Chemical Company

(MFR (190° C.)=0.5 g/10 min, number of monomer unit derived fromethylene=88%, melting temperature=55° C., [CC]=1.7 dl/g, density=0.868g/cm³)

(C-2) ethylene-1-octene copolymer

Engage® 8100 Manufactured by the Dow Chemical Company

(MFR (190° C.)=1 g/10 min, number of monomer unit derived fromethylene=89%, melting temperature=60° C., [CC]=1.5 dl/g, density=0.870g/cm³)

(D-1) ethylene-propylene-5-ethylidene-2-norbornene copolymer

(MFR (190° C.)=0.2 g/10 min, number of monomer unit derived fromethylene=76%, iodine value=4, melting temperature=10° C., [ηD]=2.2 dl/g,density=0.859 g/cm³)

(D-2) ethylene-1-butene copolymer

Engage® HM 7487 manufactured by The Dow Chemical Company

(MFR (190° C.)=0.2 g/10 min, [RD]=1.9 dl/g, number of monomer unitderived from ethylene=80%, melting temperature=37° C., density=0.860g/cm³)

(D-3) ethylene-1-butene copolymer

Engage® 7467 manufactured by The Dow Chemical Company

(MFR (190° C.)=1.2 g/10 min, [ηD]=1.5 dl/g, number of monomer unitderived from ethylene=82%, melting temperature=34° C., density=0.862g/cm³)

Eerucamide (Neutron S manufactured by Nippon Fine Chemical Co., Ltd.)

Antioxidant 1: SUMILIZER® GA80 manufactured by Sumitomo Chemical Co.,Ltd.

Antioxidant 2: IRGAFOS® 168 manufactured by BASF Japan Ltd.

Light stabilizer 1: SUMISORB® 300 manufactured by Sumitomo Chemical Co.,Ltd.

Light stabilizer 2: TINUVIN® 622SF manufactured by BASF Japan Ltd.

Light stabilizer 3: TINUVIN® 123 manufactured by BASF Japan Ltd.

Preservative: hydrotalcite (DHT-4A manufactured by Kyowa ChemicalIndustry Co., Ltd.)

Inorganic filler: calcium carbonate (Vigot10 manufactured by ShiraishiCalcium Kaisha Ltd.)

Example 1

Forty five (45) % by weight of a heterophasic propylene polymerizationmaterial comprising (A-1-1) and (B-1), 5% by weight of the polymer(A-2-1), 30% by weight of the ethylene-1-octene copolymer (C-1) and 20%by weight of the ethylene-propylene-5-ethylidene-2-norbornene copolymer(D-1) when the sum of (A-1-1), (A-2-1), (B-1), (C-1) and (D-1) is 100%by weight,

and 0.05 parts by weight of erucamide, 0.2 parts by weight of anantioxidant 1, 0.1 part by weight of an antioxidant 2, 0.2 parts byweight of a light stabilizer 1, 0.1 part by weight of a light stabilizer2, 0.1 part by weight of a light stabilizer 3, 0.2 parts by weight of apreservative and 0.6 parts by weight of an inorganic filler, withrespect to 100 parts by weight of the total of the (A-1-1), (A-2-1),(B-1), (C-1) and (D-1), were melt-kneaded by a twin screw extruder at acylinder temperature of 200° C., to obtain thermoplastic elastomercompositions. The resultant thermoplastic elastomer compositions wereinjection-molded by the method 9, to obtain injection molded bodies, andcomposite molded bodies were obtained by the method 12. The results ofmeasurement of physical properties of the injection molded bodies andthe composite molded bodies are shown in Table 1. The intrinsicviscosity of the propylene-based polymer was determined by substituting[ηcxis] of the heterophasic propylene polymerization material and theintrinsic viscosity of (A-2-1) into the formula (1).

Example 2 to 3 and Comparative Examples 1 to 5

Thermoplastic elastomer compositions were produced in the same manner asin Example 1 with components and contents shown in Table 1. Theresultant thermoplastic elastomer compositions were injection-molded bythe method 9, to obtain injection molded bodies, and composite moldedbodies were obtained by the method 12. The results of measurement ofphysical properties of the injection molded bodies and the compositemolded bodies are shown in Table 1.

TABLE 1 Com. Com. Com. Com. Com. Ex. 1 Ex. 2 Ex. 3 Ex. 1 Ex. 2 Ex. 3 Ex.4 Ex. 5 (A-1-1) + (B-1) 45 47 42 50 45 45 48 (A-1-2) + (B-2) 45 (A-2-1)5 5 4 5 5 2 (A-2-2) 5 (C-1) 30 39 (C-2) 30 25 30 30 30 (D-1) 20 17 25 20(D-2) 18 20 20 20 (D-3) 30 Erucamide 0.05 0.05 0.05 0.05 0.05 0.05 0.050.05 Antioxidant 1 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Antioxidant 2 0.1 0.10.1 0.1 0.1 0.1 0.1 0.1 Light stabilizer 1 0.2 0.2 0.2 0.2 0.2 0.2 0.20.2 Light stabilizer 2 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Light stabilizer3 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Preservative 0.2 0.2 0.2 0.2 0.2 0.20.2 0.2 Inorganic filler 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 [η]A d1/g 1.141.13 1.11 0.9 1.14 1.33 0.95 1 MFR of thermoplastic g/10 min 7 8 8 9 8 811 10 elastomer composition (230° C.) Bending elastic MPa 100 110 100 90110 100 100 90 modulus (90° C.) Izod impact strength −45° C. kJ/m² 95 8385 33 99 72 81 82 NB or B NB NB NB B NB B B B Welding strength MPa 8 8.18.7 8.5 7.5 7.7 7.7 8.1 D7 nm 97 115 — — — 122 119 132 D200 nm 384 445 —— — 336 375 374 D200/D7 — 4 3.9 — — — 2.8 3.2 2.8

DESCRIPTION OF REFERENCE NUMERALS

-   -   1: second molded body    -   2: first molded body    -   3: welded part

The invention claimed is:
 1. A composite molded body in which a firstmolded body comprising a propylene-based polymer and a second moldedbody comprising a thermoplastic elastomer composition are welded witheach other, wherein when the cross-sectional surface perpendicular tothe welding surface is stained with a vapor of ruthenium tetraoxide, thestained domain satisfies requirement (1); Requirement (1): when thestained cross-sectional surface is observed with a transmission electronmicroscope, D7 is 115 nm or less, wherein D7 is a number-averagecircle-equivalent diameter of the stained domain in a square having aside of 4 μm around a point where the distance from the welded part is 7μm in a vertical direction, wherein the square presents in the secondmolded body.
 2. The composite molded body according to claim 1, whereinwhen the cross-sectional surface perpendicular to the welding surface isstained with a vapor of ruthenium tetraoxide, the stained domainsatisfies requirement (2); Requirement (2): when the stainedcross-sectional surface is observed with a transmission electronmicroscope, D200/D7 is 3.5 or more, wherein D200 is a number-averagecircle-equivalent diameter of the stained domain in a square having aside of 4 μm around a point where the distance from the welded part is200 μm in a vertical direction, wherein the square present in the secondmolded body.
 3. The composite molded body according to claim 1, whereinthe first molded body and the second molded body are vibrated and weldedwith each other.
 4. An automobile interior part comprising the compositemolded body according to claim 1.